Durgapur, Sept. 7: For the second time in three days, the Delimitation Commission today witnessed Mamata Banerjee's politics of disruption, which left it worried about the fate of tomorrow's sitting in Calcutta.

Commission members were hearing the public's suggestions on the proposed redrawing of constituencies at the Srijoni auditorium here when Trinamul Congress workers barged in and rained shoes and water bottles on them.

'Commission members and some officials were abused and threatened; the public address system was damaged. Since the situation threatened to go out of control (we) decided to close the public sitting,' commission secretary Shangara Ram said.

The trouble spilled over to the neighbourhood with Trinamul workers on the rampage for two hours, stoning police, smashing up three police jeeps and three other vehicles, and attempting to set fire to a bus.

With Mamata egging party workers on to do a repeat in Calcutta, security has been beefed up in and around Mahajati Sadan, the venue for tomorrow's public hearing. 'The Rapid Action Force will be deployed,' home secretary Amit Kiran Deb said.

Trinamul had disrupted Monday's hearing in Siliguri, too. Mamata had squatted on the road with 4,000 supporters, demanding the commission chairman, Justice (retd) Kuldip Singh, hear over 1,000 petitions in three hours.

Today, she was in town but stayed away from the scene of vandalism. But key Trinamul functionaries, such as leader of the Opposition Pankaj Banerjee, chief whip Sobbhandeb Chattopadhyay, president Subrata Bakshi and MLAs Saugata Roy, Tamanash Ghosh, Malay Ghatak and Apurba Mukherjee, led from the front.

They jumped onto the dais and tried to snatch the microphone from commission member and Left Front chief whip Rabin Deb. Then nearly 1,000 Trinamul supporters stormed the venue, hurled water bottles and shoes on the dais and shouted slogans against commission members.

'The delimitation is a farce as it is being dictated by the CPM,' many in the mob kept chanting.

Without naming Mamata or Trinamul, the commission said the mob had seemed to act in a well-planned manner.

'We were shocked to notice that right from the beginning, attempts were made by the leaders of a particular political party and the section of the public apparently sympathetic to that party to disrupt the proceedings,' Ram said.

The violence outside injured Burdwan superintendent of police Piyush Pande, additional superintendent Satyajit Banerjee and eight other policemen. The police had to teargas the mob after a baton-charge proved futile. Twenty Trinamul workers were injured and an equal number arrested.

Later, Trinamul supporters blocked roads, including National Highway 2, disrupting traffic for over two hours.

'The public hearing is a farce,' Mamata later said at a rally on a football ground opposite the auditorium.

Tomorrow, 2,000 police and RAF personnel will be posted outside Mahajati Sadan. An additional commissioner and two joint commissioners will oversee security with eight deputy commissioners. City detective chief Gyanwant Singh will be inside the hall.

The proceedings will be shown live on a television set placed at Marques Square.